Electric heating unit.



H. M. SMITH. LEGTRIG HEATING UNIT.

IOATION FILED MAR. 29. 1909.

962,793. Patented June 28,1910.

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Inventor;

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HERBERT M. SMITH, OF PITTSI IELD, MASSACHUSETTS, ASSIGNOB TO GENERALELECTRIC COMPANY, A CORPORATION OF NEW YORK.

ELECTRIC HEATING UNIT.

Specification of Letters Patent. P te -ten June 25, 1910.

Application filed. March 29. 1909.

Serial No. 486,418.

the arrangement being such that the casing is bent around the unitwithout injury either to the unit or to the metal of the casing.

In carrying out my invention, I employ in connection with a fiat heatingunit, a container for the unit which is bent over it in such a way as tohold it'firmly in place. It

has been found necessary to use relatively heavy metal for forming thiscasing, which requires a hard blow and great pressure to close down.Moreover, in closing down the metal flange around the unit, the greatpressure used in the folding operation bruises the mica insulation andrenders the insulation imperfect so that short circuits are liable toresult. To overcome this objection, I have cut away the metal at thepoint where the bend occurs, thus grinding a weak line where the shellis to be folded over.

Other obj ects of my invention will appear in the course of thefollowing specification,

in which I have shown my invention embodied in cncrete form for purposesof illustration.

In the accompanying drawings, embodying' my invention, Figure 1 is asectional plan View of my device; Fig. 2 is a sectional elevation of thesame on the line 22; Fig. 3 shows a fragmentary detail of the cupshapedcasing; and Fig. 4 shows a fragmentary detail of a modified form...

Referring to the drawings, 10 and 11 represent two sections of a heatingunit arranged in the form of concentric rings, one within and spacedfrom the other. This particular arrangement of heating unit forms no'art of my invention but. I have shown it or purposes of illustration.Furthermore, this particular arrangement of unit is disclosed in anapplication filed by J. C. Logan, Serial No. 484,692, filed March 20,1909, and requires no further description aside from the means which Iprovide for keeping the unit central. within the casing.

Generally speaking, the unit consists of two mica rin s mounted within acup-shaped casing 12. This casing may be of any desired material,asforinstance, steel or iron. Inorder to hold the outer ring rigidlywithin the casing so that the wires will not touch the casing, I formprojections 13 on the mica at various points around the ring, whichengage the casing. The cup-shaped portion 12 is provided with boltshaving heads l4;

brazed to the inner side to project into the cup-shaped portion. Theinner ring 11 is likewise provided with projecting portions 16 whichreceive the shanks of the bolts 15 to hold the ring in place. A plate 17fits snugly into the casing so as to cover the resistance conductor,rings of mica or other insulating material 18 and 19 being applied toeach side of the conductors to insulate and protect them from thecasing. In order to bend the cup-shaped casing over the plate 17 withoutinjuring the insulation, I reduce the metal at the bend. In Fig. 3 Ihave shown the metal reduced by being entirely cut away or counterboredat 20. This cnables the metal to be bent down more easily upon the plate17, thus closing the parts firmly together without injury. In Fig. 1 Ihave shown another method of bringing about this result, which consistsin forming a V-shaped groove 21 in the casing at a point Where the bendoccurs. The ring of insulation 22 is secured to the plate 17 by thebolts 15 as shown, and the terminals of the resistance conductor arebrought down to the terminal pins 23, which are mounted in theinsulating ring.

While I have shown and described my invention as embodied in concreteform for purposes of illustration, I do not desire to limit my inventionthereto, since various modifications thereof will suggest themselves tothose skilled in the artwithout departing from the spirit of myinvention, the scope of which is set forth in the annexed claims.

W hat I claim as new and desire to secure by Letters Patent of theUnited states, is,

1. An electric heater comprising a fiat heating unitand a cup-shapedcontainer therefor bent over the unit and having the metal reduced atthe bend.

2. An electric heater comprising a flat heating unit, a cup-shapedcontainer therefor and a late covering said unit, said container beingent upon the plate and having the metal reduced at the bend.

3. An electric heater comprising a flat heating unit and a containertherefor bent over the unit and having the metal reduced at the bend.

4. An electric heater comprising a flat heating unit, a circularcontainer therefor bent over the unit and having the metal reduced atthe bend.

5. An electric heater comprising a heating unit, a cup-shaped containertherefor bent over the unit and having the metal reduced at the bend.

6. An electric heater comprising a fiat heating unit, a circularcup-shaped container 8. An electric heater comprising a metal casing, aheating element, and mica insulation covering the element havingprojecting lugs to center the element and its insulation.

In witness whereof, I have hereunto set my hand this 23rd day of March,1909.

HERBERT M. SMITH.

' Witnesses:

P. A. SMITH, F. G. LARAMEE.

